The British government could soon roll ahead with plans to issue national ID cards after both houses of Parliament reached a compromise Wednesday night on a bill detailing the plan.

The House of Lords voted an amendment to the bill on Wednesday night, making receiving the card optional until Jan. 1, 2010. The House of Commons then also approved the revised bill. A representative of Prime Minister Tony Blair said the opt-out date "strikes a sensible compromise."

Those who apply for a passport before that date, however, will still be entered in a database called the National Identity Register, part of the ID card system. After the deadline, the card will become mandatory for anyone applying for a designated identity document such as a passport.

Peers in the House of Lords amended the bill several times amid privacy concerns, resisting the government's desire to make the card mandatory when the program started.

The bill now moves to royal approval, the last step before becoming law.

The Home Office wants to start issuing ID cards by 2008. While strong opposition surfaced against making the cards mandatory, the government maintains national ID cards will strengthen national security, reduce benefits fraud and enhance immigration controls.

The U.K. is gradually implementing new "ePassports" with a chip containing a scan of the holder's unique facial features. It's envisioned the ID card will also contain biometric details such as fingerprints and iris patterns.

The government has estimated the plan will cost around £584 million (US$1 billion) per year. An ID card lasting 10 years would cost £30 (US$52) to issue, and a new passport £63. The increased costs come from implementing the National Identity Register and the cost of producing the ID cards, the Home Office has said.

The London School of Economics has contested the estimate, however, saying the program's costs could be twice the government's figure. The government said it would not release further details of its costs studies so as not to taint a future procurement process.

A Home Office official contacted Thursday morning could not immediately detail the next step in the program if the bill is approved into law.